Cylinder for internal combustion engine



June 28, 1966 BROOKS 3,257,998

CYLINDER FOR INTERNAL COMBUSTION ENGINE Filed Feb. 4. 1965 2 Sheets-Sheet 1 v I g. g Z.

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WHANN a McMAN/GAL Af/ofneys for A l/can/ June 28, 1966 J. H. BROOKS 3,257,998

7 CYLINDER FOR INTERNAL COMBUSTION ENGINE Filed Feb. 4, 1965 2 Sheets-Sheet 2 Join I Brooks,

INVENTOR.

WHANN 8 McMA/WGAL for/my: for fl I/cwr/ d-mm United States Patent Office 3,257,998 Patented June 28, 1966 3,257,998 CYLINDER FOR INTERNAL COMBUSTIGN ENGINE dolm H. Brooks, Encino, Calif., assignor to McCulloch Corporation, Los Angelcs, Calif., a corporation of Wisconsin Filed Feb. 4, 1965, Ser. No. 430,340 9 Claims. (Cl. 123-73) This invention relates generally to internal combustion engines and relates more particularly to cylinders for two-cycle engines.

The scavenging of the combustion gases from the cylinder bores of two-cycle engines has long been a problem.

As is well known, combustion gases are exhausted or scavenged from the cylinder bore through exhaust ports in the cylinder wall which are uncovered by the piston during the latter part of its down stroke. Expulsion of the combustion gases is effected by a fluid scavenging medium admitted or injected into the cylinder through an intake port or ports in the cylinder wall and also uncovered by the piston in its down stroke.

The inlet and exhaust ports are arranged to effect as great as possible a scavenging action of the exhaust gases with a minimum loss of scavenging fluid, which may be a fuel mmture and, hence, such loss adversely affects the efficiency of the engine. Among the problems involved in this type of arrangement is the proper directing of the incoming scavenging fluid, so that a maximum of combustion products in the cylinder will be removed during the exhaust portion of the engine operation with a minimum loss of the scavenging fluid.

The manufacture or production of cylinders for such two-cycle engines comes rather expensive since it involves drilling of ports and doing other machine work thereon.

It is an object ofthe invention to provide a cylinder that will solve these problems and difficulties.

It is therefore another object of the present invention to provide cylinders for two-cycle internal combustion engines wherein the drilling of ports is eliminated.

Another object of the invention is to provide cylinders of this character wherein extra machining costs are eliminated.

It'is still another object of the invention to provide cylinders of this character wherein there is a substantial saving in assembly costs.

It is a further object of the invention to provide cylinders of this character having a cylinder liner in which the ports are cast.

It is a still further object of the invention to provide cylinders having cast liners with the porting cast therein and the intake porting arrangement includes blisters that extend outwardly of the exterior of the cast lines and when the liner is cast in the cylinder head these blisters aid in anchoring the liner therein.

It is a still further object of the invention to provide a cylinder having a liner of this character which may be re-bore'd without affecting the porting.

It is another object of the invention to reduce the external dimensions of the cylinder by eliminating the normal wall between the piston and scavenge canal.

The characteristics and advantages of the invention are further sufficiently referred to in connection with the following detailed description of the accompanying drawings, which represent one embodiment. After considering this example skilled persons will understand that many variations may be made without departing from the principles disclosed, and I contemplate the employment of any structures, arrangements, or modes of operation that are properly within the scope of the appended claims.

Referring to the drawings, which are for illustrative purposes only:

FIG. 1 is a longitudinal section through the upper part of an engine having a cylinder embodying the present invention, the piston being located in the cylinder intermediate the ends of its stroke;

FIG. 2 is a similar view showing the piston after it has moved upwardly in the cylinder to close the ports;

FIG. 3 is a view through the cylinder with the piston at approximately upper dead center;

F 216. 4 is a view of the cylinder taken on line 44 of FIG. 5 is a sectional view of the cylinder liner taken on line 55 of FIG. 4; and

FIG. 6 is a diagrammatic, longitudinal section through the engine at right angles to FIG. 1.

Referring more particularly to the drawings, there is shown the upper part of a two-cycle internal combustion engine, indicated generally at 10, having a cylinder block 11 and the upper part 12 of a crankcase, indicated generally at 14-. The crankcase is of any suitable well known type and has an engine crankshaft, not shown.

While the engine may be water cooled, it is shown as being of the air cooled type and the cylinder block is provided with a plurality of cooling fins 15 of the usual character and arrangement. There is a cylinder head 16 which is shown as being integral with the cylinder block but, it is to be understood, the cylinder head could be a separate part secured to the cylinder block by any suitable well known means and in any suitable well known manner. The cylinder head is also provided with cooling fins 17 and there is a combustion chamber 18 in the inner side of said cylinder head.

A liner, indicated generally at 20, is cast in the cylinder block, said liner also being cast of suitable material, such as, for example, iron.

Liner 20 has a longitudinally extending interior bore 21 defined by a wall 22, said bore 21 being open at both ends.

An upper end portion of the liner wall 22 is provided with a plurality of external, annular ribs spaced apart longitudinally or axially and when the liner is cast in the cylinder block said ribs securely anchor same in position in said cylinder block and against any longitudinal displacement. At one side the liner is provided with a boss 24 having a pair of exhaust passages 25 which are in communication with the bore'21 of the liner by way of exhaust ports 26. While two passages 25 are shown and described, it is to be understood that there may be but one such passage or more than two. These exhaust ports are disposed at an intermediate position relative to the length of the liner and are adapted to be controlled by a piston 28 reciprocably mounted in the bore 21.

At the opposite side of the liner there is an external boss 29 having an inlet passage 30 therethrough which communicates with the bore 21 of the liner by means of an inlet port 31. Inlet port 31 is positioned below the exhaust ports 26 and said inlet port 31 is adapted to be controlled by said piston 28 and uncovered when the piston is in an upper range of movement.

At generally right angles to the bosses 24 and 29 for the exhaust and inlet passages, the liner is provided with diametrically arranged bosses or what may be termed blisters 33. Each of these blisters has transfer passage means. There may be one or a plurality thereof, there being three such passages or channels shown and given reference numbers 35, 36 and 37, respectively. These passages are inclined upwardly and away from the side of the cylinder or bore 21 having the exhaust ports 26,

the upper ends of said passages being at substantially the same level and terminating in a horizontal plane below the plane of the top of the exhaust ports 26. The lower ends of the passages or channels 35, 36 and 37 are shown as terminating upwardly of the lower end of the cylinder or bore 21.

Piston 28 has a piston head 28a. and a skirt 2811 having openings 28c therein at diametrically opposite sides and at the sides having the bosses or blisters 33, said openings 280 being adapted to communicate with some or all of the passages 35, 36 and 37 at various piston positions.

The general sequence of engine operation Assuming that the engine is in operation and starting the description of such operation with the piston at lower dead center, the openings 280 in the piston skirt will be in communication with the transfer passages or channels 35, 36 and 37. A fuel mixture has been drawn into the crankcase interior 17 and compressed therein by the downstroke movement of the piston. At this time the inlet port 31 is, of course, closed by the piston skirt and the exhaust ports 26 are uncovered and open.

For the first 45 to 70 of crankcase rotation from bottom dead center the transfer or scavening channels 35, 36 and 37 are open so that the fuel mixture charge in the crankcase may flow therefrom through the passages 35, 36 and 37 into the cylinder above the piston. For the first 55 to 90 of crankshaft rotation from the bottom dead center the exhaust ports are open to facilitate scavening flow of combustion products therefrom. As the piston moves upwardly it begins to cover the exhaust ports 26 and the upper ends of the transfer passages 35, 36 and 37. When the piston head or the top of the piston reaches the upper edges of the transfer passages 35, 36 and 37 said passages are closed against the flow of fuel mixture upwardly into the upper portion of the cylinder 21. This occurs before the upper end of the piston reaches the upper edges of the exhaust ports 26, so that the exhaust ports remain open for a longer period than the transfer passages. When the upper end of the piston reaches the upper edges of the exhaust ports the latter are fully closed and the fuel mixture charge in the cylinder above the piston is compressed with further upward movement of the piston. In FIG. 2 the piston is shown as having reached a position fully covering or closing the exhaust ports.

As the piston moves upwardly from this position the fuel mixture is compressed in the upper part of the cylinder above the piston and in the combustion chamber 18. At the same time the skirt of the piston begins to uncover the inlet port 31 which is connected with the carburetor or other charge forming device. The upward movement of the piston has created a partial vacuum in the crankcase and as soon as the piston skirt begins to uncover the inlet port 31 a fresh charge of fuel mixture begins to be drawn through the inlet port 31, and thence into the bore or cylinder 21 and into the crankcase interior 17 with which the piston is in full communication.

When the piston has reached upper dead center, as shown in FIG. 3, and the fuel mixture in the upper end of the cylinder and combustion chamber 18 has been fully compressed, it is then ignited in the usual manner, such as, for example, a spark plug 18a. Upon ignition of this fuel mixture in the combustion chamber the piston is driven downwardly in its power stroke. As the piston moves downwardly it first reaches the upper edges of the exhaust ports and begins to uncover said ports so that the exhaust gases or combustion products begin to escape through said ports. At the same time the piston has closed the inlet port 31 and begun to compress the fresh fuel mixture charge in the crankcase interior 17.

Upon further downward movement of the piston the upper ends of transfer passages 35, 36 and 37 are uncovered and since the openings 28c in the piston skirt communicate with said transfer passages the fuel mixture being compressed in the crankcase flows through the openings 28c and into the transfer passages 35, 36 and 37 and thence upwardly into the upper part of the cylinder. Because of the inclination of the transfer passages 35, 36 and 37 away from the side of the cylinder having the exhaust ports the fresh charge of fuel or the fuel mixture flows upwardly in the upper part of the cylinder toward the side away from the exhaust ports and circulates so as to clear out or scavenge the combustion product in the upper end of the cylinder and the combustion chamber 18 and drive such combustion products downwardly along the side of the cylinder having the exhaust ports and thence out of said exhaust ports.

The invention and its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts of the invention without departing from the spirit and scope thereof or sacrificing its material advantages, the arrangement hereinbefore described being merely by way of example, and I do not wish to be restricted to the specific form or uses mentioned except as defined in the accompanying claims, wherein various parts or portions have been separated for clarity of reading and not for emphasis.

I claim:

1. In a two-cycle internal combustion engine assembly:

(A) a cast iron cylinder liner having a longitudinally extending cylindrical bore therethrough open at both ends, said cylinder liner having (a) a plurality of annular, longitudinally spaced external ribs on an upper end portion,

(b) a boss at one side having a pair of exhaust passages therein communicating with the bore of said liner by means of ports,

(c) said exhaust ports being located intermediate the ends of the liner and intermediate the ends of the stroke of a piston reciprocably mounted in said bore,

(d) a second boss having an inlet passage therethrough communicating with the cylindrical bore of the liner by means of an inlet port,

(c) said inlet port being spaced closer to the inner end of the liner than said exhaust ports,

(f) a pair of blisters at right angles to the exhaust and inlet bosses and arranged diametrically opposite to each other, each of said blisters having a plurality of passages formed therein opening into said cylindrical bore and extending toward the outer end of said liner and inclined away from the side having the exhaust ports, the upper ends of said transfer passages in said blisters having their upper ends terminating longitudinally inwardly of the outer edges of the exhaust ports;

(B) a cylinder block cast about said liner and leaving the outer ends of the inlet passage and the exhaust passages free;

(C) and a piston for reciprocable motion within the bore of the liner, said piston having a head and a skirt, the latter having oppositely arranged openings therein adapted to be in communication with the transfer passages whereby fluid from the crankcase of the engine may pass into the piston, through said openings in the skirt thereof, thence into the transfer passages and into the upper end of the bore of the liner, said inlet port, exhaust ports and transfer passages being controlled by the piston.

2. In a two-cycle internal combustion engine assembly:

(A) a cylinder liner having a longitudinally extending cylindrical bore therethrough open at both ends, said cylinder liner having (a) a boss at one side having an exhaust passage therein communicating with the interior bore of said liner by means of an exhaust port,

(b) said exhaust port being located intermediate the ends of the liner and intermediate the ends of the stroke of a piston reciprocably mounted in said bore,

(c) a second boss having an inlet passage therethrouh communicating with the cylindrical bore of the liner by means of an inlet port,

((1) said inlet port being spaced closer to the inner end of the liner than said exhaust port,

(e) at least one blister at substantially right angles to the exhaust and inlet bosses, said blister having a plurality of passages formed therein having at least a portion of their length opening into said bore and extending toward the 'outer end of said liner and inclined away from the side having the exhaust port, the upper ends of said transfer passages in said blisters having their upper ends terminating inwardly of the outer edge of the exhaust port;

(B) a cylinder block cast about said liner and leaving the outer ends of the inlet passage and the exhaust passage free;

(C) and a piston for reciprocable motion within the bore of the liner, said piston having a head and a skirt, the latter having an opening therein adapted to be in communication with the transfer passages whereby fluid from the crankcase of the engine may pass'into the piston, through said opening in the skirt thereof, thence into the transfer passages and into the upper end of the bore of the liner, said inlet port, exhaust port and transfer passages being controlled by the piston.

3. In a two-cycle internal combustion engine assembly:

(A) a cast iron cylinder liner having a longitudinally extending cylindrical bore therein, said cylinder liner having (a) an exhaust port communicating with the interior bore of said liner,

(b) said exhaust port being located intermediate the ends of the stroke of a piston reciprocably mounted in said bore,

(c) an inlet port communicating with the cylindrical bore of the liner,

((1) said inlet port being spaced closer to the inner end of the liner than said exhaust port,

(e) at least one blister spaced circumferentially from said exhaust port approximately 90, said blister having at least one passage formed therein extending toward the outer end of said liner and inclined away from the exhaust port, said transfer passage being open along at least a portion of the inner side and having its upper end terminating inwardly of the outer edge of the exhaust P (B) a cylinder block cast about said liner;

(C) and a piston for reciprocable motion within the bore of the liner, said piston having a head and a skirt, the latter having an opening therein adapted to be in communication with the transfer passage whereby fiuid from the crankcase of the engine may pass into the piston through said opening in the skirt thereof, thence into the transfer passage and into the upper end of the bore of the liner, said inlet port, exhaust port and transfer passage being controlled by the piston. 4. In a two-cycle internal combustion engine assembly: (A) a cast iron cylinder liner having a longitudinally extending cylindrical bore therein, said cylinder liner having (a) an exhaust port communicating with the interior bore of said liner, (b) said exhaust port being located intermediate the ends of the stroke of a piston reciprocably mounted in said bore,

ing a cylinder having a piston receiving bore extending longitudinally therein, said cylinder having (c) an inlet port communicating with the cylindrical bore of the liner,

((1) said inlet port being spaced closer to the inner end of the liner than said exhaust port,

(e) at least one blister spaced circumferentially from said exhaust port approximately said blister having at least one passage formed therein extending toward the outer end of said liner and inclined away from the exhaust port, said transfer passage being'open along at least a portion of the inner side and having its upper end terminating inwardly of the outer edge of the exhaust port;

(B) and a cylinder block cast about said liner.

5. In an internal combustion engine:

(A) a cast cylinder block;

(B) a cast cylinder liner cast into said cylinder block, said cylinder liner having a piston receiving cylinder bore extending longitudinally therethrough and open at both ends, said liner including (a) a boss at one side intermediate the ends thereof and having at least one exhaust passage therethrough communicating with the bore through the liner by means of an exhaust port, 7

(b) a second external boss on the liner at the di metrically opposite side thereof from the exexhaust port and having an inlet passage therethrough communicating with the bore of the liner by means of an inlet port spaced closer to the inner end of the liner than said exhaust port,

(c) and at least one blister at right angles to said bosses, said blister having at least one transfer passage therein extending longitudinally of the cylinder liner and inclined toward the outer end and away from the exhaust port, said transfer passage terminating at its outer end longitudinally of the outer edge of the exhaust port;

(C) and a piston adapted for reciprocal motion in the bore of the liner and controlling said ports and passage.

6. In an internal combustion engine:

(A) a cast cylinder block;

(B) a cast cylinder liner cast into said cylinder block, said cylinder liner having a piston receiving cylinder bore extending longitudinally therein, said liner having (a) a boss at one side intermediate the ends thereof and having at least one exhaust passage therethrough communicating with the bore through the liner by means of an exhaust port,

(-1)) a second external boss on the liner at the diametrically opposite side thereof from the exhaust port and having an inlet passage therethrough communicating with the bore of the liner by means of an inlet port spaced closer to the inner end of the liner than said exhaust port,

(c) and at least one blister at right angles to said bosses, said blister having at least one transfer passage therein extending longitudinally of the cylinder liner and inclined toward the outer end and away from the exhaust port, said transfer passage terminating at its outer end longitudinally inwardly of the outer edge of the exhaust port.

7. In an internal combustion engine; wall means defin- (a) at least one exhaust passage therein communicating with the piston receiving bore by means of an exhaust port,

(b) an inlet passage communicating with said piston receiving bore by means of an inlet port, said inlet port being spaced closer to the inner end of said cylinder than said exhaust port,

(c) at least one blister positioned at an angle to said ports, a plurality of generally parallel transfer passages in said blister, said passages being inclined toward the outer end of the bore away from the exhaust port, the transfer passage adjacent the exhaust port being shorter than the other passages, the outer ends of said transfer passages terminating in substantially the same plane normal to the axis of the cylinder, the inner ends of said passages terminating short of the inner end of the cylinder with the shorter passages having their inner ends spaced further outwardly longitudinally of the cylinder than the inner ends of the longer passages.

8. The invention defined in claim 7, including a second blister positioned diametrically opposite the first mentioned blister, said. second blister also having a plurality of generally parallel transfer passages therein and the passages in said second blister being substantially similar to the passages in said first blister.

9. The invention defined in claim 8, a piston in said cylinder, said piston having openings therein at diametrically opposite sides and at the sides having said blisters, said openings being so dimensioned as to be in communication with some of said passages at various piston positions.

References Cited by the Examiner UNITED STATES PATENTS MARK NEWMAN, Primary Examiner.

FRED E. ENGELTHALER, Examiner.

W. E. BURNS, Assistant Examiner. 

1. IN A TWO-CYCLE INTERNAL COMBUSTION ENGINE ASSEMBLY: (A) A CAST IRON CYLINDER LINER HAVING A LONGITUDINALLY EXTENDING CYLINDRICAL BORE THERETHROUGH OPEN AT BOTH ENDS, SAID CYLINDER LINER HAVING (A) A PLURALITY OF ANNULAR, LONGITUDINALLY SPACED EXTERNAL RIBS ON AN UPPER END PORTION, (B) A BOSS AT ONE SIDE HAVING A PAIR OF EXHAUST PASSAGES THEREIN COMMUNICATING WITH THE BORE OF SAID LINER BY MEANS OF PORTS, (C) SAID EXHAUST PORTS BEING LOCATED INTERMEDIATE THE ENDS OF THE LINER AND INTERMEDIATE THE ENDS OF THE STROKE OF A PISTON RECIPROCABLY MOUNTED IN SAID BORE, (D) A SECOND BOSS HAVING AN INLET PASSAGE THERETHROUGH COMMUNICATING WITH THE CYLINDRICAL BORE OF THE LINER BY MEANS OF AN INLET PORT, (E) SAID INLET PORT BEING SPACED CLOSER TO THE INNER END OF THE LINER THAN SAID EXHAUST PORTS, (F) A PAIR OF BLISTERS AT RIGHT ANGLES TO THE EXHAUST AND INLET BOSSES AND ARRANGED DIAMETRICALLY OPPOSITE TO EACH OTHER, EACH OF SAID BLISTERS HAVING A PLURALITY OF PASSAGES FORMED THEREIN OPENING INTO SAID CYLINDRICAL BORE AND EXTENDING TOWARD THE OUTER END OF SAID LINER AND INCLINED AWAY FROM THE SIDE HAVING THE EXHAUST PORTS, THE UPPER ENDS OF SAID TRANSFER PASSAGES IN SAID BLISTERS HAVING THEIR UPPER ENDS TERMINATING LONGITUDINALLY INWARDLY OF THE OUTER EDGES OF THE EXHAUST PORTS; (B) A CYLINDER BLOCK CAST ABOUT SAID LINER AND LEAVING THE OUTER ENDS OF THE INLET PASSAGE AND THE EXHAUST PASSAGES FREE; (C) AND A PISTON FOR RECIPROCABLE MOTION WITHIN THE BORE OF THE LINER, SAID PISTON HAVING A HEAD AND A SKIRT, THE LATTER HAVING OPPOSITELY ARRANGED OPENINGS THEREIN ADAPTED TO BE IN COMMUNICATION WITH THE TRANSFER PASSAGES WHEREBY FLUID FROM THE CRANKCASE OF THE ENGINE MAY PASS INTO THE PISTON, THROUGH SAID OPENINGS IN THE SKIRT THEREOF, THENCE INTO THE TRANSFER PASSAGES AND INTO THE UPPER END OF THE BORE OF THE LINER, SAID INLET PORT, EXHAUST PORTS AND TRANSFER PASSAGES BEING CONTROLLED BY THE PISTON. 